Patent GB-749248-A (GB)
Title: Improvements in or relating to epicyclic change-speed gearing
Inventor: BROWN WILLIAM
IPC: B62M11/14
Filed: 1952-11-17
Abstract: 749,248. Change-speed gears. STURMEY-ARCHER GEARS, Ltd. Nov. 3, 1953 [Nov. 17, 1952; May 20, 1953], Nos. 28917/52 and 14118/53. Class 80(2) Relates to planetary changespeed gearing, for pedal bicycles, comprising a stationary sun gear 1a, planet gears 2 on a planet carrier 3 and an internally toothed annulus 5. Two pawl and ratchet couplings are provided, the first (5c, 17b. Fig. 1) between the annulus and an output member or hub 9 and the second, 6b, 6a, between the planet carrier and the output member. A slidable selective clutch member 22 couples an input member 14 either to the planet carrier or the annulus, in the latter position also rendering the first ratchet coupling 5a, 17b inoperative. According to the invention, the first ratchet coupling consists of a ring 17, separate from the selective clutch member 22, having two sets of coupling formations (17b, 17a, Fig. 1) complementary to coupling formations (5c, 12a) on the annulus 5 and output member 9, one such set of coupling formations (5c, 17b) providing ratchet coupling and the ring sliding to engage or disengage one or other of the sets of coupling formations, one set of the coupling formations being formed on the end faces of the ring and annulus. A sleeve 19 and pin 20 in a stationary axle 1 are slidable under the control of a rod 21 to move the selective clutch member 22 axially of the gear. The clutch member 22 has projections 22a engaging in slots 14a in the input member 14. The projections 22a can also be engaged either with dogs 3b on the planet carrier, by allowing the clutch member 22 to be moved to the left of Fig. 1 by a spring 24, or, as shown, with splines 5b on the annulus 5. When the clutch member 22 is moved 135 to the right as shown in the upper half of Fig. 1, it carries the ratchet ring 17 with it against the force of a spring 18 and disengages the ratchet teeth 5c, 17b. In this position, a step-down drive is obtained from the input member 14 through slots 14a, clutch member 22, projections 22a, splines 5b, the annulus and the planets 2 to the planet carrier 3 and ratchet clutch 6b, 8a. By allowing the clutch member 22 to be moved by the spring 24 to the middle position shown in the lower half of Fig. 1, direct drive is obtained,.as the input member is now connected to the annulus 5 and drive passes through the now engaged ratchet teeth 17b, 5c to the ratchet ring 17 and thence through the teeth 17a, engaging the splines 12a, to the hub 9. On allowing the ring 22 to be moved further to the left to engage the projections 22a with the dogs 3b on the planet carrier, a step-up drive is obtained from the input member 14, through the ring 22, planet carrier 3b, planets 2, annulus 5, ratchet teeth 5c, 17b, ring 17 and teeth, &c., 17a, 12a, the ratchet coupling 6b, 8a, overrunning. In one modification, a ratchet coupling having radially acting pawls 17d, Fig. 4, is provided between the ring 17 and the hub. In the extreme right-hand position of the ring 17 shown in the upper half of Fig. 4, a step-down drive is obtained through the input member 14, ring 22, annulus 5, &c. When the selective clutch member 22 is moved to the middle position shown in the lower half of this Figure, the ring 17 is moved to the left by the spring 18 and dogs 17g thereon engage dogs 5e on the annulus to give. direct drive. In the extreme left-hand position of the clutch member 22, the projections 22a thereon engage pinion pins 3a on the carrier for a step-up drive. In a further modification, radially acting pawls 30, Fig. 8, on a pawl ring 28 replacing the ring 17, are disengaged from teeth 31a in the hub 9 when the ring is moved to its extreme right-hand position for step-down drive. The ring 28 has lugs permanently engaging dogs 29a on the annulus 5.